"She has the whole package. ... This girl is nasty. She might be beautiful on the outside, but she's a Diaz brother on the inside. She's a real fighter and real talented. She has the credentials and the pedigree. And she has the 'it' factor. I think she's going to be a big superstar."

Terms of the deal, as well as a debut date and opponent, were not disclosed.

Rousey (6-0 MMA, 4-0 Strikeforce), an Olympic bronze-medal judoka, likely will become the UFC's women's bantamweight championship as her title changes promotions. As of now, she's the only confirmed female fighter signed to the organization.

Rousey, in a short window of time, has taken the MMA world by storm. She ran through three amateur opponents with first-round armbars, and she did the same to her first four pro opponents.

She got a title shot in March against then-Strikeforce champ Miesha Tate, and though Tate lasted longer than all of Rousey's previous opponents combined, she still was forced to tap to a first-round arm bar. In her first title defense in August, Rousey also submitted Sarah Kaufman â?? by armbar â?? in less than a minute.

Many fans are eager to see a fight between Rousey and Cristiane "Cyborg" Santos, who was stripped of her title and issued a yearlong suspension after a failed drug test (steroids) last December. But Santos has been hesitant to drop from 145 pounds, where she was Strikeforce's champion, at her doctors' urging.

Rousey's move comes amid rumors of Strikeforce's likely demise after a final show Jan. 12. Rousey isn't scheduled to compete in the event, which features three other champions from the promotion.